Argo Vulnerable to Unauthenticated Memory Exhaustion (DoS) in Webhook Interceptor

NVD Description

**Severity:** Medium **Component:** Webhook Interceptor (`server/auth/webhook`) **Vulnerability Type:** Denial of Service (DoS) ## Description The Webhook Interceptor loads the entire request body into memory before authenticating the request or verifying its signature. This occurs on the `/api/v1/events/` endpoint, which is publicly accessible (albeit intended for webhooks). An attacker can send a request with an extremely large body (e.g., multiple gigabytes), causing the Argo Server to allocate excessive memory, potentially leading to an Out-Of-Memory (OOM) crash and denial of service. ## Vulnerable Code In `server/auth/webhook/interceptor.go`: ```go func (i *WebhookInterceptor) addWebhookAuthorization(r *http.Request, kube kubernetes.Interface) error { // ... basic checks ... // Vulnerability: Reads entire body into memory unconditionally buf, _ := io.ReadAll(r.Body) defer func() { r.Body = io.NopCloser(bytes.NewBuffer(buf)) }() // ... subsequent logic finds correct service account and secret ... // ... verification happens later ... } ``` The `io.ReadAll` call happens before the signature verification loop. ## Impact - **Service Availability:** An attacker can crash the Argo Server, disrupting workflow execution and API access for all users. ## PoC (Conceptual) 1. Target the webhook endpoint: `POST /api/v1/events/some-namespace` 2. Send a `Content-Length: 1000000000` (1GB) header. 3. Stream 1GB of random data. 4. Monitor server memory usage. It will spike until 1GB is allocated or the process crashes. ## Recommendation 1. **Limit Body Size:** Enforce a strict limit on webhook body size (e.g., 10MB) using `http.MaxBytesReader`. 2. **Streaming Verification:** If possible, verify the signature in a streaming fashion or use a temporary file for large payloads (though typically webhooks are small).

Affected Packages (2)